JP2863160B1 - Phosphorescent phosphor - Google Patents

Abstract

The present invention provides a phosphorescent phosphor that has a shorter excitation time and a higher persistence luminance than a conventional aluminate phosphor, and also achieves a long persistence time. SOLUTION: It is activated by divalent europium, and its chemical composition formula is RO · a (Al _1-x Ga _x ) ₂ O ₃ · b (Y _1-y
Sc _y ) ₂ O ₃ .cB ₂ O ₃ .dEu ²⁺ .eM ^{n +} (where R
Is at least one member selected from the group consisting of alkaline earth metals such as Ba, Sr, Ca, Mg and Zn, and M is a coactivator, and Nb, Zr, Bi, Mn, Sn,
La, Ce, Pr, Nd, Sm, Gd, Tb, Dy, H
o, Er, Tm, Yb, Lu, at least one selected from the group consisting of), a, b, c, d,
e, x, y are respectively 0.3 ≦ a ≦ 8, 0 ≦ b ≦ 0.
2,0.001 ≦ c ≦ 0.2, 0.001 ≦ d ≦ 0.
3,0.001 ≦ e ≦ 0.3,0 ≦ x <1.0,0 ≦ y
A luminous phosphor which is in the range of ≦ 1.0.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

[0001] The present invention relates to a compound of formula RO
_{· A (Al 1-x Ga} x) 2 O 3 · b (Y 1-y Sc y) 2 O 3 · cB 2
O ₃ .dEu ²⁺ .eM ^{n +} (where R is Ba, Sr, C
a, at least one selected from the group consisting of alkaline earth metals such as Mg and Zn, and M is a coactivator, and Nb, Zr, Bi, Mn, Sn, La, Ce, P
r, Nd, Sm, Gd, Tb, Dy, Ho, Er, T
at least one member selected from the group consisting of m, Yb, and Lu), which has a new light emission with a fast rise time, a high afterglow luminance, a long afterglow time, and various emission wavelengths. The present invention relates to a phosphorescent phosphor.

[0002]

2. Description of the Related Art Fluorescence is a phenomenon in which a substance emits light in the vicinity of the visible region when stimulated (excited) from the outside. Fluorescent lamps, discharge lamps, CRTs (Cathode Ray Tubes) are known.
e) This is light emission from a so-called CRT. A substance that emits fluorescence is called a phosphor. If the fluorescence continues for a time (about 0.1 second) that can be felt by the eyes after the excitation is stopped,
This is called phosphorescence, and a phosphor having a long afterglow such that the phosphorescence lasts for several hours at room temperature is called a phosphorescent phosphor.

[0003] Regarding the phosphorescent phosphor, ZnS:
Two types of sulfides represented by Cu and oxides using RAl ₂ O ₄ (R: alkaline earth metal) as a mother crystal have been reported. The ZnS: Cu sulfide phosphorescent light was put into practical use several decades ago, but has a problem that the afterglow time is as short as about 3 hours at most. Further, this phosphorescent phosphor is decomposed into ZnS + H ₂ O → Zn + H ₂ S by coexistence with ultraviolet rays contained in sunlight and moisture contained in the atmosphere,
The particles themselves have a fatal disadvantage that the particles themselves are blackened, the afterglow luminance is gradually reduced, and the function is significantly reduced in a short period of time.
For this reason, this kind of luminous body has been limited mainly to very limited uses such as a luminous clock and an indoor night display.

[0004] On the other hand, a recently developed oxide phosphor having a base crystal of RAl ₂ O ₄ and activated by Eu ²⁺ (US Pat. No. 53,531)
No. 76303, U.S. Pat.
-73845, JP-A-8-127772, JP-A-8-127
No. -15574) has a characteristic that the afterglow time is longer than that of ZnS: Cu, and it is also excellent in chemical durability and light resistance. It is expected to be used in a wide range of applications, such as danger prevention displays for position recognition and decorations.

However, these existing phosphorescent phosphors are still insufficient in afterglow luminance with the expansion of application fields, and it has been desired to improve them. In addition, a characteristic of being excited quickly in a short time has been strongly desired.

[0006]

SUMMARY OF THE INVENTION The present invention has been made in view of the above circumstances, and has been developed by using alkali activated by Eu ²⁺ which has greatly improved afterglow luminance and at the same time greatly reduced the excitation time. An object of the present invention is to provide an earth metal aluminate phosphorescent phosphor.

[0007]

The inventor of the present invention has proposed an existing Eu.
As a result of conducting detailed experiments on alkaline earth metal aluminate phosphors activated by ²⁺ , the above object was achieved by further adding yttrium oxide or scandium oxide to these phosphors to achieve the present invention. Was reached.

That is, the invention according to claim 1 is an alkaline earth metal aluminate phosphorescent phosphor activated by divalent europium, and its chemical composition formula is RO · a
_{(Al 1-x Ga x)} 2 O 3 · b (Y 1-y Sc y) 2 O 3 · cB 2 O 3 ·
dEu ²⁺ .eM ^{n +} (where R is Ba, Sr, Ca, Mg
And at least one member selected from the group consisting of alkaline earth metals and Zn, and M is a coactivator;
Zr, Bi, Mn, Sn, La, Ce, Pr, Nd, S
m, Gd, Tb, Dy, Ho, Er, Tm, Yb, Lu
A, b, c, d, e, x, y are each 0.3
≦ a ≦ 8, 0 <b ≦ 0.2, 0.001 ≦ c ≦ 0.2,
0.001 ≦ d ≦ 0.3, 0.001 ≦ e ≦ 0.3, 0
≦ x <1.0, 0 ≦ y ≦ 1.0 is a phosphorescent phosphor, wherein the invention according to claim 2,
characterized in that in mol% containing from 0.001 to 8% of Li, a phosphorescent phosphor according to claim 1, the invention according to claim 3, CaAl ₂ O ₄ and Ca (Rm ,
Y) Al (Al ₂ O ₇ ) crystal (where Rm is Eu, Dy,
Sc, La, Ce, Pr, Nd, Sm, Gd, Tb, H
at least one element selected from the group consisting of o, Er, Tm, Yb, and Lu).
Or the phosphorescent phosphor according to any one of claims 2 to 4, wherein the invention according to claim 4 comprises CaAl ₂ O ₄ and Ca
Characterized in that it comprises a (Eu, Nd, Y) Al (Al 2 O 7) crystals are phosphorescent phosphor according to claim 3, the invention of claim 5, SrAl ₂ O ₄ and (Rm,
Y) AlO ₃ crystal (Rm is Eu, Dy, Sc, L
a, Ce, Pr, Nd, Sm, Gd, Tb, Ho, E
3. The phosphorescent phosphor according to claim 1, wherein the phosphorescent phosphor contains at least one element selected from the group consisting of r, Tm, Yb, and Lu). The invention described in (1) describes SrAl ₂ O ₄ and (Eu, D
y, Y) AlO _3, characterized in that it comprises a crystal, a phosphorescent phosphor according to claim 5, the invention according to claim 7, Sr ₄ Al ₁₄ O ₂₅ and Al ₅ (Rm, Y ) ₃ O ₁₂ crystal (where Rm is Eu, Dy, Sc, La, Ce, P
r, Nd, Sm, Gd, Tb, Ho, Er, Tm, Y
b, at least one element selected from Lu)
The phosphorescent phosphor according to any one of claims 1 to 2, characterized in that it contains Sr ₄ Al ₁₄ O ₂₅ and Al ₅ (Eu, Dy). ,
Characterized in that it comprises a Y) ₃ O ₁₂ crystals, a phosphorescent phosphor according to claim 7.

In the phosphorescent phosphor of the present invention, a is Al
The composition ratio of ₂ O ₃ + Ga ₂ O ₃ or Al ₂ O ₃ , and b is Y ₂ O ₃
+ Sc ₂ O ₃ or the composition ratio of Y ₂ O ₃ and Sc ₂ O ₃ . A remarkable improvement in the afterglow luminance was observed by increasing b to 0.2 in the range of a to 0.3 to 8, but when it was further increased, the afterglow luminance was rather lowered. c is B ₂ O ₃
Which is effective for increasing the afterglow luminance in the range of 0.001 to 0.2. d indicates the concentration of the activator, and should be in the range of 0.001 ≦ d ≦ 0.3. If d is less than 0.001, the light absorption is poor, and the afterglow luminance that can be recognized by the naked eye cannot be obtained. Conversely, if d exceeds 0.3, concentration quenching occurs and the afterglow luminance decreases. e indicates the concentration of the co-activator and should be in the range of 0.001 ≦ e ≦ 0.3. When e is less than 0.001, the effect of improving the afterglow time and afterglow brightness is weak, and when it exceeds 0.3, the afterglow brightness gradually decreases.

X represents the substitution rate when Al is replaced by Ga. By replacing a part of Al with Ga, the conventional ZnS: Cu
For example, a better phosphor can be realized. Al can be replaced with Ga by almost 100%. However, in order to obtain better characteristics, the range of x ≦ 0.5 is preferable, and the range of x ≦ 0.2 is particularly preferable. Range.

[0011] y indicates the substitution rate when Y is replaced with Sc. The substitution can be performed at 100%.
_{Since the} raw material cost increases remarkably as the content of ₂ O ₃ increases, it is preferable that y is smaller than 0.2.

Further, the addition of Li to the phosphor described in claim 1 further increases the afterglow luminance. The amount is 0.
If it is less than 001%, the effect is weak, and if it exceeds 8%, the afterglow luminance is rather lowered. Therefore, the amount of Li added is set to 0.1.
It should be limited to the range of 001 to 8%. If a remarkable effect is to be obtained, the range of 0.005 to 5% is preferable.

The Y ₂ O ₃ component is indispensable for improving the afterglow luminance. In the above-mentioned limited range, the phosphorescent phosphor having an emission peak near a wavelength of 440 nm by X-ray diffraction has a CaAl ₂ O ₃ content. O ₄ and Ca (Rm, Y) Al
(Al ₂ O ₇ ) crystal (where Rm is Eu, Dy, Sc, L
a, Ce, Pr, Nd, Sm, Gd, Tb, Ho, E
r, Tm, Yb, at least one element) selected from the group consisting of Lu, the phosphorescent phosphor having an emission peak in the vicinity of a wavelength of 520nm is, SrAl ₂ O ₄ and (R
m, Y) AlO ₃ crystal (Rm is Eu, Dy, S
c, La, Ce, Pr, Nd, Sm, Gd, Tb, H
o, Er, Tm, Yb, at least one element) selected from the group consisting of Lu, the phosphorescent phosphor having an emission peak in the vicinity of a wavelength of 490nm is, Sr ₄ Al ₁₄ O ₂₅
And Al ₅ (Rm, Y) ₃ O ₁₂ crystal (where Rm is E
u, Dy, Sc, La, Ce, Pr, Nd, Sm, G
d, Tb, Ho, Er, Tm, Yb, and Lu).

From these results, it is estimated that a part of the added Y ₂ O ₃ was dissolved in the aluminate crystal, but the remaining part which could not be dissolved was precipitated as the second layer. In the former case, it is considered that Y ³⁺ contributes to the promotion or stabilization of the generation of carrier traps that directly contribute to afterglow, and in the latter case, it is considered that the trimming of aluminate crystals contributes to the stabilization of the traps. Therefore, the afterglow luminance is greatly increased by adding Y ₂ O ₃ , as shown in Examples later.
The excitation time was also reduced by a factor of two or more.

The reason why these afterglow characteristics (afterglow luminance and afterglow time) were particularly good is that, in the phosphorescent phosphor having an emission peak near a wavelength of 440 nm, CaAl ₂ O ₄ and C
a (Eu, Nd, Y) Al (Al ₂ O ₇ )
In the phosphorescent phosphor having an emission peak near 20 nm, SrAl ₂ O ₄ and (Eu, Dy, Y) AlO ₃
In a phosphorescent phosphor having an emission peak near a wavelength of 490 nm, Sr ₄ Al ₁₄ O ₂₅ and SrAl ₂ O ₄
And Al ₅ (Eu, Dy, Y) ₃ O ₁₂ crystal.

When synthesizing the phosphorescent phosphor of the present invention, a phosphorus compound such as NH ₄ H ₂ PO ₄ may be used as a flux.
A halide such as NH ₄ F, NH ₄ Cl, NH ₄ Br, etc. can be added. The optimum amount is mol%
Is in the range of 0.05 to 8.

[0017]

DESCRIPTION OF THE PREFERRED EMBODIMENTS The phosphorescent phosphor of the present invention can be synthesized by the following sintering method. In addition, this application is not limited only to the following Examples.

First, the following materials can be used as a raw material of the phosphorescent phosphor of the present invention. (1) Regarding RO components, oxides, carbonates, nitrates,
Halides and the like. (2) For Al ₂ O ₃ component, oxides, nitrates, hydroxides, halides. (3) For Y ₂ O ₃ component, oxides, nitrates, halides and the like. (4) Rm components include oxides, carbonates, nitrates,
Halides and the like. (5) Regarding the Li component, Li ₂ CO ₃ , LiNO ₃ ,
Li ₂ SO ₄ , Li ₃ BO ₃ , Li ₂ SiO ₃ , Li ₃ PO ₄ ,
Li ₃ WO ₃ , Li ₃ MoO ₃ , halides and the like.

The above-mentioned raw materials are weighed and thoroughly mixed, and then put into an alumina crucible and placed in a reducing atmosphere at 1100 to 1600.
Bake for 1 to 10 hours. The fired product obtained by the composition may be pulverized and fired again under the same conditions.

[0020]

EXAMPLE 1 of _{CaCO 3 7.22g Al 2 O 3 7.37g} Y 2 O 3 0.03g H 3 BO 3 0.18g Eu 2 O 3 0.10g Nd 2 O 3 0.10g The above blend composition The raw materials were sufficiently mixed and calcined at 1350 ° C. for 2 hours in a mixed gas stream of 97N ₂ + 3H ₂ , and the composition formula C
_{aO · Al 2 O 3 · 0.002Y} 2 O 3 · 0.02B 2 O 3 ·
To obtain a phosphorescent phosphor comprising a _{0.004Eu 2 O 3 · 0.004Nd 2 O} 3. This phosphorescent substance has a light emission characteristic having a peak at around 440 nm, blue light is visually observed, and afterglow can be recognized in a dark place for 24 hours or more.

Examples 2 to 10 and Comparative Example A having the same emission color were prepared in the same manner as in Example 1, and their compositions are summarized in Table 1. The obtained phosphor was subjected to CaAl ₂ O ₄ and Ca (Eu, Nd, Y) Al (Al
₂ O ₇ ). Further, afterglow luminance was measured for these phosphors. Afterglow brightness is D
A 65 light source (FL20S.D-EDL-D65, manufactured by Toshiba Lighting & Technology Corporation) was irradiated at 200 lux for 4 minutes, and the afterglow luminance was measured with a luminance meter.

Table 1 summarizes the relative values of Examples 1 to 10 with the afterglow luminance of Comparative Example A 10 minutes after stopping the excitation as 100. FIG. 1 shows emission spectra of Example 4 and Comparative Example A 10 minutes after stopping the excitation. As is clear from Table 1 and FIG. 1, afterglow luminance or luminous intensity was greatly improved by adding Y ₂ O ₃ to the conventional blue-emitting aluminate phosphor.

FIG. 2 shows the relationship between the irradiation time and the afterglow luminance immediately after the excitation was stopped when the fluorescent phosphors of Example 4 and Comparative Example A were excited at an illuminance of 200 lux using the above light source. This is shown in the graph.

The time required for the afterglow luminance to be saturated is about 45 minutes for the conventional phosphor, while that for the phosphor of the present invention is about 20 minutes, and it is necessary to reach 80% of the saturation luminance. The time is about 10 minutes for the phosphor of the present invention, while the conventional phosphor takes about 25 minutes. It was found that the phosphor of the present invention containing Y ₂ O ₃ not only increased the afterglow luminance but also efficiently absorbed the excitation light, and the excitation time was reduced by a factor of 2 or more.

[0025]

[Table 1]

Further, Pr, Sm, G together with the co-activator Nd
Examples 11 to 1 in which d, Ho, Er, Tm, and Lu were added
7 and Comparative Example were produced in the same manner as in Example 1.
Table 2 summarizes their compositions and the relative afterglow luminance 10 minutes after the excitation was stopped. Table 2 shows that the phosphor of the present invention exhibits a higher afterglow luminance.

[0027]

[Table 2]

[0028]

Example 18 SrCO ₃ 8.64 g Al ₂ O ₃ 5.97 g Y ₂ O ₃ 0.03 g H ₃ BO ₃ 0.14 g Eu ₂ O ₃ 0.10 g Dy ₂ O ₃ 0.11 g The raw materials were sufficiently mixed and fired at 1350 ° C. for 2 hours in a mixed gas stream of 97N ₂ + 3H ₂ , and the composition formula S
_{rO · Al 2 O 3 · 0.002Y} 2 O 3 · 0.02B 2 O 3 ·
To obtain a phosphorescent phosphor comprising a _{0.005Eu 2 O 3 · 0.005Dy 2 O} 3. This phosphorescent substance has a light emission characteristic having a peak near 520 nm, yellow-green light emission is visually observed, and afterglow can be recognized in a dark place for 24 hours or more.

In the same manner as in Example 18, Examples 19 to 23 and Comparative Example B having the same emission color were produced. Table 3 summarizes their compositions and the relative afterglow luminance after one minute. X-ray diffraction analysis revealed that the obtained phosphor contained SrAl ₂ O ₄ and (Eu, Dy, Y) AlO ₃ crystal phases. FIG. 3 shows emission spectra of Example 21 and Comparative Example B one minute after stopping the excitation.

From Table 3 and FIG. 3, Y ₂ O ₃ or Sc ₂ O ₃
It has been found that the phosphor of the present invention containing the compound has high afterglow luminance and emits strong light. Table 3 also shows that the addition of lithium further increased the afterglow luminance.

[0031]

[Table 3]

[0032]

Example 24 SrCO ₃ 6.58 g Al ₂ O ₃ 7.95 g Y ₂ O ₃ 0.03 g H ₃ BO ₃ 0.30 g Eu ₂ O ₃ 0.07 g Dy ₂ O ₃ 0.07 g The raw materials are sufficiently mixed and fired at 1450 ° C. for 2 hours in a mixed gas stream of 97N ₂ + 3H ₂ , and the composition formula S
_{rO · 1.75Al 2 O 3 · 0.003Y} 2 O 3 · 0.06
A luminous phosphor composed of B ₂ O ₃ .0.004 Eu ₂ O ₃ .0.004 Dy ₂ O ₃ was obtained. This phosphorescent phosphor is 490n
It has emission characteristics having a peak near m, blue-green emission can be visually observed, and afterglow can be recognized in a dark place for 24 hours or more.

Example 24 Examples 25 to 28 and Comparative Example C having the same emission color were produced in the same manner. Table 5 summarizes their compositions and the relative afterglow luminance after one minute. The obtained phosphor was subjected to Sr ₄ Al ₁₄ O ₂₅ and Sr
It was found to contain Al ₂ O ₄ and Al ₅ (Eu, Dy, Y) ₃ O ₁₂ crystals. FIG. 4 shows emission spectra of Example 26 and Comparative Example C one minute after stopping the excitation. Table 4 and FIG.
From this, it has been clarified that the phosphor of the present invention in which Y ₂ O ₃ is added to the conventional blue-green luminescent aluminate phosphor has a high afterglow luminance and emits more intense light.

FIG. 5 shows an SEM photograph of Comparative Example C. 6 and 7 show SEM photographs of Examples 25 and 27, respectively. These SEM photographs show that the addition of Y ₂ O ₃ increases the crystal grain size of the phosphorescent phosphor.

[0035]

[Table 4]

[0036]

[Light resistance test] Since phosphorescent phosphors are often used by being directly exposed to sunlight, they must be strong against sunlight, especially ultraviolet rays contained therein. So, JI
The phosphor obtained in the present invention was subjected to a light resistance test using a 300 W mercury lamp according to the test method for light resistance of a luminescent paint according to the S standard. As a result, no decrease in afterglow luminance was observed in any of the samples.

[Brief description of the drawings]

FIG. 1 is an emission spectrum of Example 4 and Comparative Example A 10 minutes after stopping excitation.

FIG. 2 is a graph showing a change in afterglow luminance with irradiation time immediately after excitation is stopped.

FIG. 3 is an emission spectrum of Example 21 and Comparative Example B one minute after stopping the excitation.

FIG. 4 is an emission spectrum one minute after stopping excitation in Example 26 and Comparative Example C.

FIG. 5 is an SEM photograph of Comparative Example C.

FIG. 6 is a SEM photograph of Example 25.

FIG. 7 is an SEM photograph of Example 27.

Claims (8)

(57) [Claims] 1. An alkaline earth metal aluminate phosphorescent phosphor activated with divalent europium, the chemical composition of which is RO.a (Al _1-x Ga _x ) ₂ O ₃ .b (Y _1-y Sc _y )
₂ O ₃ .cB ₂ O ₃ .dEu ²⁺ .eM ^{n +} (where R is Ba,
Mn is at least one member selected from the group consisting of alkaline earth metals such as Sr, Ca, Mg and Zn, and M is a coactivator, and Nb, Zr, Bi, Mn, Sn, La, C
e, Pr, Nd, Sm, Gd, Tb, Dy, Ho, E
at least one selected from the group consisting of r, Tm, Yb, and Lu), a, b, c, d, e,
x and y are respectively 0.3 ≦ a ≦ 8, 0 <b ≦ 0.2,
0.001 ≦ c ≦ 0.2, 0.001 ≦ d ≦ 0.3,
0.001 ≦ e ≦ 0.3, 0 ≦ x <1.0, 0 ≦ y ≦
A phosphorescent phosphor which is in the range of 1.0. 2. The luminous phosphor according to claim 1, comprising 0.001 to 8% by mol of Li. 3. CaAl ₂ O ₄ and Ca (Rm, Y) A
l (Al ₂ O ₇ ) crystal (where Rm is Eu, Dy, Sc,
La, Ce, Pr, Nd, Sm, Gd, Tb, Ho, E
The phosphorescent phosphor according to any one of claims 1 to 2, wherein the phosphorescent phosphor contains at least one element selected from the group consisting of r, Tm, Yb, and Lu). 4. CaAl ₂ O ₄ and Ca (Eu, Nd,
Characterized in that it comprises a _{Y) Al (Al 2 O 7} ) crystals, phosphorescent phosphor according to claim 3. 5. SrAl ₂ O ₄ and (Rm, Y) AlO
₃ crystals (Rm is Eu, Dy, Sc, La, Ce,
Pr, Nd, Sm, Gd, Tb, Ho, Er, Tm, Y
b, at least one element selected from Lu)
The phosphorescent phosphor according to any one of claims 1 to 2, characterized by comprising: 6. The phosphorescent phosphor according to claim 5, wherein the phosphorescent phosphor contains SrAl ₂ O ₄ and (Eu, Dy, Y) AlO ₃ crystals. 7. Sr ₄ Al ₁₄ O ₂₅ and Al ₅ (Rm,
Y) ₃ O ₁₂ crystal (Rm is Eu, Dy, Sc, L
a, Ce, Pr, Nd, Sm, Gd, Tb, Ho, E
The phosphorescent phosphor according to any one of claims 1 to 2, wherein the phosphorescent phosphor contains at least one element selected from the group consisting of r, Tm, Yb, and Lu). 8. Sr ₄ Al ₁₄ O ₂₅ and Al ₅ (Eu, D
8. The composition according to claim 7, which comprises a (y, Y) ₃ O ₁₂ crystal.
3. The phosphorescent phosphor according to item 1.